UNIQUE PROBLEMS IN MODELING IRRIGATION CANALS

This is one of several introductory papers resulting from work by the ASCE Task Committee on Irrigation Canal System Hydraulic Modeling. It is intended to serve as background for analyses by the Task Committee of several available programs. Irrigation-canal modeling is based on t he same unsteady-flow equations used for river modeling. However. the canal and irrigation environment present several unique simulation pro blems generally not encountered in river modeling. These include zero- depth conditions, mixed-regime and reversing flow, gate submergence, f low in inverted siphons and culverts multiple flow paths, and control- system interfaces. This paper outlines some of these special problems, discusses their importance, and reviews some solution approaches in g eneral terms.